Method and apparatus for extruding glass tubing

Abstract

An apparatus (10) for extruding glass tubing (12) which comprises a furnace (14). A component (16) within the furnace (14) is for holding molten glass (18). A duplex mandrel (20) on one end of the furnace (14) is connected into the holding component (16). A facility (22) is for forcing the molten glass (18) in the holding component (16) out through the duplex mandrel (20), so as to form the glass tubing (12) having an upper support segment (24) and a lower structural segment (26). An assembly (28) is for quick cooling the upper support segment (24) of the glass tubing (12) upon exiting the duplex mandrel (20), so that the lower structural segment (26) will maintain its desired shape while slow cooling.

What is claimed is new and desired to be protected by Letters Patent is set forth in the appended claims: 
     
       1. An apparatus for extruding glass tubing which comprises: a) a furnace;   b) means within said furnace for holding molten glass;   c) a duplex mandrel on one end of said furnace connected into said holding means;   d) means for forcing the molten glass in said holding means out through said duplex mandrel, so as to form the glass tubing having an upper support segment and a lower structural segment; and   e) means for quick cooling said upper support segment of said glass tubing upon exiting said duplex mandrel, so that said lower structural segment will maintain its desired shape while slow cooling.   
     
     
       2. An apparatus for extruding glass tubing as recited in claim 1, wherein said furnace includes: a) a housing to encompass said holding means;   b) a burner within said housing to provide heat for the molten glass in said holding means;   c) an external fuel tank; and   d) a fuel line extending between said external fuel tank and said burner.   
     
     
       3. An apparatus for extruding glass tubing as recited in claim 1, wherein said holding means is a ceramic vessel. 
     
     
       4. An apparatus for extruding glass tubing as recited in claim 1, wherein said forcing means includes: a) a pressure plate within said holding means opposite from said duplex mandrel; and   b) means for operating said pressure plate, which will push against the molten glass and cause the molten glass to exit said duplex mandrel.   
     
     
       5. An apparatus for extruding glass tubing as recited in claim 4, wherein said operating means includes: a) a casing affixed to said furnace opposite from said duplex mandrel;   b) a threaded drive shaft extending from said casing through said furnace and to said pressure plate within said holding means;   c) a motor carried within said casing adjacent said threaded drive shaft; and   d) a drive gear connected to said motor and in engagement with said threaded drive shaft, which will cause said pressure plate to push against the molten glass.   
     
     
       6. An apparatus for extruding glass tubing as recited in claim 1, wherein said quick cooling means includes: a) a fan to supply air under pressure;   b) a pipe extending from said fan and terminating slightly past and above a forward end of said duplex mandrel; and   c) an air nozzle on a distal free end of said pipe, whereby said air nozzle is positioned to face downwardly over said upper support segment of said glass tubing after exiting said duplex mandrel.   
     
     
       7. A method of extruding glass tubing comprising the steps of: a) holding molten glass in a ceramic vessel within a furnace;   b) forcing the molten glass out through a duplex mandrel on one end of said furnace that is connected into said ceramic vessel, so as to form said glass tubing having an upper support segment and a lower structural segment; and   c) quick cooling said upper support segment of said glass tubing upon exiting said duplex mandrel, so that said lower structural segment will maintain its desired shape while slow cooling.   
     
     
       8. A method as recited in claim 7, wherein said furnace includes: a) a housing to encompass said ceramic vessel;   b) a burner within said housing to provide heat for the molten glass in said ceramic vessel;   c) an external fuel tank; and   d) a fuel line extending between said external fuel tank and said burner.   
     
     
       9. A method as recited in claim 7, wherein said step b) includes operating a pressure plate within said ceramic vessel opposite from said duplex mandrel, whereby said pressure plate will push against the molten glass and cause the molten glass to exit said duplex mandrel. 
     
     
       10. A method as recited in claim 7, wherein step c) includes: a) a fan to supply air under pressure;   b) a pipe extending from said fan and terminating slightly past and above a forward end of said duplex mandrel; and   c) an air nozzle on a distal free end of said pipe, whereby said air nozzle is positioned to face downwardly over said upper support segment of said elongate glass tube after exiting said duplex mandrel.   
     
     
       11. An apparatus for extruding glass tubing which comprises: a) a furnace, wherein said furnace includes a housing to encompass said holding means, a burner within said housing to provide heat for the molten glass in said holding means, an external fuel tank and a fuel line extending between said external fuel tank and said burner;   b) means within said furnace for holding molten glass;   c) a duplex mandrel on one end of said furnace connected into said holding means;   d) means for forcing the molten glass in said holding means out through said duplex mandrel, so as to form the glass tubing having an upper support segment and a lower structural segment; and   e) means for quick cooling said upper support segment of said glass tubing upon exiting said duplex mandrel, so that said lower structural segment will maintain its desired shape while slow cooling.   
     
     
       12. An apparatus for extruding glass tubing as recited in claim 11, wherein said holding means is a ceramic vessel. 
     
     
       13. An apparatus for extruding glass tubing as recited in claim 12, wherein said forcing means includes: a) a pressure plate within said holding means opposite from said duplex mandrel; and   b) means for operating said pressure plate, which will push against the molten glass and cause the molten glass to exit said duplex mandrel.   
     
     
       14. An apparatus for extruding glass tubing as recited in claim 13, wherein said operating means includes: a) a casing affixed to said furnace opposite from said duplex mandrel;   b) a threaded drive shaft extending from said casing through said furnace and to said pressure plate within said holding means;   c) a motor carried within said casing adjacent said threaded drive shaft; and   d) a drive gear connected to said motor and in engagement with said threaded drive shaft, which will cause said pressure plate to push against the molten glass.   
     
     
       15. An apparatus for extruding glass tubing as recited in claim 16, wherein said quick cooling means includes: a) a fan to supply air under pressure;   b) a pipe extending from said fan and terminating slightly past and above a forward end of said duplex mandrel; and   c) an air nozzle on a distal free end of said pipe, whereby said air nozzle is positioned to face downwardly over said upper support segment of said glass tubing after exiting said duplex mandrel.   
     
     
       16. A method of extruding glass tubing comprising the steps of: a) holding molten glass in a ceramic vessel within a furnace, wherein said furnace includes a housing to encompass said ceramic vessel, a burner within said housing to provide heat for the molten glass in said ceramic vessel, an external fuel tank and a fuel line extending between said external fuel tank and said burner;   b) forcing the molten glass out through a duplex mandrel on one end of said furnace that is connected into said ceramic vessel, so as to form said glass tubing having an upper support segment and a lower structural segment; and   c) quick cooling said upper support segment of said glass tubing upon exiting said duplex mandrel, so that said lower structural segment will maintain its desired shape while slow cooling.   
     
     
       17. A method as recited in claim 16, wherein said step b) includes operating a pressure plate within said ceramic vessel opposite from said duplex mandrel, whereby said pressure plate will push against the molten glass and cause the molten glass to exit said duplex mandrel. 
     
     
       18. A method as recited in claim 17, wherein step c) includes: a) a fan to supply air under pressure;   b) a pipe extending from said fan and terminating slightly past and above a forward end of said duplex mandrel; and   c) an air nozzle on a distal free end of said pipe, whereby said air nozzle is positioned to face downwardly over said upper support segment of said elongate glass tube after exiting said duplex mandrel.